This application is based upon, claims the benefit of priority of, and incorporates by reference the contents of prior Japanese Patent Applications No. 2001-297274 filed on Sep. 27, 2001, No. 2002-103522 filed on Apr. 5, 2002, and No. 2002-211243 filed on Jul. 19, 2002.
1. Field of the Invention
The present invention relates to a vehicle air conditioning system that utilizes carbon dioxide or a hydrocarbon-based refrigerant, such as propane, as a refrigerant. More specifically, the invention involves an air switching mode to mix and direct outside air to an upper vehicle compartment to alter the air a driver inhales.
2. Description of Related Art
Vehicle air conditioning systems may experience refrigerant leaks as a consequence of interior heat exchanger cracks, which may be corrosion induced. When carbon dioxide or hydrocarbon-based refrigerants, such as propane, are used, refrigerant that leaks from the heat exchanger and into the passenger compartment may affect the health of the driver.
This problem has been addressed by providing means, upon detecting refrigerant leakage, for stopping the air conditioning system and closing an opening portion made in the air conditioning casing normally used to blow air. This arrangement, however, cannot maintain a comfortable passenger compartment temperature for the driver. Moreover, there is a possibility that adequate and safe visibility cannot be guaranteed if fogging occurs on the window glass, particularly in the winter when the outside air temperature is low.
The present invention has been devised in view of the foregoing, and therefore, has the object to at least prevent the driver""s health from being affected in the event of refrigerant leakage.
In order to achieve the above object, a first aspect of the invention entails a heat exchanger for exchanging heat between air to be blown into a passenger compartment and a refrigerant, an air conditioning casing for accommodating the heat exchanger and for defining a bypass channel for directing air to a downstream side by bypassing the heat exchanger and a channel through which air having passed through the heat exchanger flows, and an air cleanliness degree detecting means for detecting a cleanliness degree of air inside the passenger compartment.
When the degree of air cleanliness detected by the air cleanliness degree detecting means decreases to or below a predetermined value, a refrigerant leaking mode is activated. In this mode, air having passed through the bypass channel is mainly blown in a direction closer to a driver and the air having passed through the heat exchanger is blown in a direction farther from the driver. Consequently, the driver""s inhalation of the refrigerant can be prevented, and therefore, should leakage of the refrigerant occur, it is possible to prevent the driver""s health from being endangered.
In another aspect of the invention, during the refrigerant leaking mode, it is preferable to blow out the air that has passed through the bypass channel, toward an upper body of the driver. Additionally, during the refrigerant leaking mode, it is preferable to blow out the air that has passed through the heat exchanger, to the driver, and more specifically, toward a lower body of the driver.
In another aspect of the invention, when carbon dioxide is used as the refrigerant, it is preferable to use a carbon dioxide sensor for detecting a concentration of carbon dioxide in air as the air cleanliness degree detecting means. Alternatively, an oxygen sensor for detecting a concentration of oxygen in air may be used as the air cleanliness degree detecting means to judge whether the air cleanliness degree decreases to or below a predetermined value when the concentration of oxygen detected by the oxygen sensor decreases to or below a predetermined concentration. Alternatively, a pressure sensor for detecting a pressure of the refrigerant may be used as the air cleanliness degree detecting means. Also, during the refrigerant leaking mode, it is preferable to configure in such a manner that air introduced from outside the passenger compartment is mainly introduced into the bypass channel.
In another aspect of the invention, the air conditioning casing is divided into at least two channels so that air introduced from inside the passenger compartment and air introduced from outside the passenger compartment are flown separately, and the bypass channel is provided in one of the two channels through which the air introduced from the outside of the passenger compartment mainly flows.
Consequently, not only can fresh air be supplied to the driver, but also mixing of air having passed through the bypass channel and being free from the refrigerant with air having passed through the heat exchanger and thereby containing a considerable quantity of the refrigerant can be prevented. This makes it reliably effective to prevent the driver""s health from being affected. Alternatively, a heater for applying heat to the air having passed through the heat exchanger may be provided. Alternatively, a heater for applying heat to the air having passed through the bypass channel may be provided.
Alternatively, a heater for applying heat to at least one of the air having passed through the heat exchanger and the air having passed through the bypass channel may be provided, and the heater may use waste heat generated in the vehicle as a heat source. The heater may use cooling water or exhaust gas of an internal combustion engine as a heat source.
Incidentally, the driver""s inhalation of the refrigerant is prevented by supplying air containing a considerable quantity of a leaked refrigerant to the lower side of the passenger compartment.
According to another aspect of the invention, during the refrigerant leaking mode, the air having passed through the heat exchanger is released outside of the passenger compartment, thereby making it possible to prevent air containing a considerable quantity of the refrigerant from flowing to the upper side of the passenger compartment. It is preferable to release the air having passed through the heat exchanger to an outside of the passenger compartment for at least a predetermined time.
In another aspect of the invention, the air having passed through the heat exchanger is discharged to the outside of the passenger compartment by way of a discharge port through which water inside the air conditioning casing is discharged. Consequently, it is possible to discharge water inside the air conditioning casing while preventing sound outside the air conditioning casing from leaking to the passenger compartment by closing the discharge port in a mode other than the refrigerant leaking mode.
In another aspect of the invention, it is preferable to provide the air conditioning casing with a discharge port with an opening and closing means through which the air having passed through the heat exchanger is discharged to the outside of the passenger compartment. The opening and closing means may have a communication hole for always allowing communication with the discharge port.
Another aspect of the invention utilizes: a heat exchanger for exchanging heat between a refrigerant and air that is to be blown into a passenger compartment, an air conditioning casing for accommodating the heat exchanger and for defining a channel through which air having passed through the heat exchanger flows, and air cleanliness degree detecting means for detecting a cleanliness degree of air inside the passenger compartment. When the air cleanliness degree detected by the air cleanliness degree detecting means decreases to or below a predetermined value, a refrigerant leaking mode is invoked, in which the air having passed through the heat exchanger is released to an outside of the passenger compartment for at least a predetermined time. Consequently, the driver""s inhalation of air containing a considerable quantity of the leaked refrigerant is prevented, thereby preventing the driver""s health from being affected.
Another aspect of the invention has: a first interior heat exchanger for exchanging heat between a refrigerant circulating through a vapor compression type refrigerator that moves heat on a low temperature side to a high temperature side and air to be blown out into a passenger compartment, a second interior heat exchanger for applying heat to the air to be blown out into the passenger compartment, an air conditioning casing for accommodating the first and second heat exchangers, and for defining a first bypass channel for directing air to a downstream side by bypassing the first heat exchanger, a second bypass channel for directing air to the downstream side by bypassing the second heat exchanger; a discharge port through which the air having passed through the first heat exchanger is discharged to an outside of the passenger compartment, and a channel through which air having passed through the first and second heat exchangers flows; and a single thin film door for controlling a ratio of air quantities between the air having passed through the second heat exchanger and the air having bypassed the second heat exchanger, a communication state of the first bypass channel, and a communication state of the discharge port.
The invention in another aspect has: a first interior heat exchanger for exchanging heat between a refrigerant circulating through a vapor compression type refrigerator that moves heat on a low temperature side to a high temperature side and air to be blown into a passenger compartment, a second interior heat exchanger for applying heat to the air to be blown into the passenger compartment, an air conditioning casing for accommodating the first and second heat exchangers and for defining a first bypass channel for flowing air to a downstream side by bypassing the first heat exchanger, a second bypass channel for flowing air to the downstream side by bypassing the second heat exchanger, a discharge port through which the air having passed through the first heat exchanger is discharged to an outside of the passenger compartment, and a channel through which air having passed through the first and second heat exchangers flows, and a single thin film door for controlling a ratio of air quantities between the air having passed through the second heat exchanger and the air having bypassed the second heat exchanger and a communication state of the discharge port.
According to another aspect of the invention, an outside wall surface of a cover covering at least an end portion of the second heat exchanger is curved, so that a movement of the film type door is guided.
According to another aspect of the invention, the discharge port is opened while an outside air mode for introducing outside air into the air conditioning casing is switched ON when a driving engine is stopped or a compressor of the vapor compression refrigerator is stopped. Consequently, it is possible to discharge the refrigerant leaked or the water vapor evaporated from the first interior heat exchanger, while the engine or the compressor is stopped, to the outside of the passenger compartment.
In another aspect the invention provides a switching means for switching between a case for introducing the refrigerant discharged from a compressor of the vapor compression refrigerator into the first interior heat exchanger without reducing a pressure of the refrigerant, and a case for introducing the refrigerant discharged from the compressor into the first interior heat exchanger after reducing the pressure of the refrigerant.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.